Apparatus for grinding toothed members



Jan. 31, 1961 D. s. CAMPBELL ,621

APPARATUS FOR GRINDING TOOTHED MEMBERS Filed Jan. 15, 1958 3 Sheets-Sheet 1 INVENTOR SM 3. W BY m amm ATTORNEY Jan. 31, 1961 D. s. CAMPBELL 2,969,621

APPARATUS FOR GRINDING TOOTHED MEMBERS Filed Jan. 15, 1958 3 Sheets-Sheet 2 T I L W E 7 7 A 24 I I 7o 7 p J l li 6'8 97 i; 50 22 i 6.0 I f 99 h /o/ j I I v I l 26 Ex\ I! in! I LUIIIIII I LI mu X W 4 4 I INVENTOR BMW S W ATTORNEY Jan. 31, 1961 D. s. CAMPBELL 2,969,621

APPARATUS FOR GRINDING TOOTHED MEMBERS Filed Jan. 15, 1958 s Sheets-Sheet 3 ATTORN EY Unite APPARATUS FOR GRINDING TOOTHED MEMBERS This invention relates to grinding machines of -the;generating type employing a helically formed or worm-like grinding wheel for grinding toothed-parts such as gears and the like, and more particularly to an improved work drive therefor.

In grinding machines of this type a two phase grinding operation has been used to secure the desired surface finish on the teeth of the work gear. This operation has involved a first grinding phase wherein the work gear and helically formed grinding wheel are interdriven through an intertimed drive connected to their respective supports and a second phase Whereinthe work gear is completely freed from the machine drive. Thus during the second phase the work gear has been controlled and driven solely by the helically formed grinding wheelso it is not subjected directly to impulses, vibrations, or other disturbances from the intertiming drive and ,animproved surface finish is obtained.

However this previous approach has been .found to have basic deficiencies. Because during the second phase the work gear is completely freed from direct connection to the'machine drive the basic accuracy of thework ,gear cannot be improved. Also during this second phase as the rotating wheel and work gear are relatively separated leave-oiFamarks often resulton the teeth of the work gear. ,Leave-off is basically a thinningon the driven side of the freely rotatable work gear where the grinding wheel lastgrinds afterthe wheel and vworkgear resiliently or yieldingly driven to effectively isolate it from disturbing irregularities in the interdrive while the work is still maintained under control of the intertime drive so that the basic form and accuracy of ,the work is maintained or improved and leave-off 'difficulties are avoided.

It .is -a further object to provide suc'h, an ,apparatus wherein releasable positive drive means and non-releasable yieldable drive means are provided inparallel in the drive to the work whereby the positive drive means canube released and disabled to render, the yieldable drive effective.

It is a further objective to provide such an apparatus including a resilient leaf spring attached between a dog on a work supporting arbor and a driven ,arbor supporting plate, cam actuated jaws being carried on the plate to grip and couple the driving dog to the platefor positive ,drive and to release the dog and .render the vleafspring effective for driving the,.arbor and work.

Other objects and advantages of'the presentinvention States Patent 2,969,621 Patented Jan. 33, 1961 ice will be apparent from the following description, the appended claims and the accompanying drawings, in which:

Figure 1 illustrates a gear grinder of a known type to which the present invention is especially applicable,

Figure 2 is a diagram of a portion of the intertiming drive between the helically formed grinding wheel and work ,gear in theillustrated machine,

Figures 3 and .4 arefragmentary diagrams illustrating the operation of the machine of Figure 1,

Figure 5 is a vvertical section through a portion of the workhead of the illustrated grinding machine and which embodies the present invention,

figure 6 is a sectional view taken on line 66 of Figure 5,

Figure 7 is a side view of the work supporting plate of the workhead and of the apparatus of the present invention shown in partial section,

-Figure 8 illustrates in perspective the parallel drive structure of this invention, and

Figures 9 and 10 illustrate this apparatus in two different drive conditions.

In the application of the present invention illustrated for-purpose of disclosing the present invention both positive and resilient drive interconnections are provided -in parallel in the :drive to the work gear. Upon release -;i ll u strates an examplary grinding machine including a base VIO supportinga workhead 11 and a wheel head 12.

.Wheel; head 12 is adjustable toward and from workhead '11 through a hand wheel 14, bevel gears 15, leadscrew 5 16, and lead nut 17 connected ;,to the wheel head. A helically formed grinding wheel -19 is driven in-timed I relation with-a work pieceor gear;20supported between centers 21 and 22 provided by workhead 11.

The work piece20 is usually mounted on .an :arbor such asthatindicated at 24 mounted between centers 21 and-22. The arbor is-driven through a dogiand parallel drive later described from a driving plate .25 forming a part of workhead 11. "Plate 25 ;is in tur -driven {through a shaft 26 and a gear interdrive shownpartially ,in Figures 2 and 5.

gReferring particularly to Figure -2 an electrical, :drive motor 30 drives directly to grinding wheel :spindle :32 through V;belts '34. Dr ive for work-support arbor .24 is taken off through worm and wormgear 35 and drives through bevel gear sets 36 and 37 to, a shaft- 40, splined at 41 within a connecting 'shaft 42. Shaft ;42 in turn drives through a gear train not illustrated to. series. spur ,gears 44, 45 and 46 and -to shaft 26. Splined interconnection 41 and 42 is; provided to maintain the. interdrive during movement pf Wheel head 12 relative to the workhead.

In the operation of such amachine the workpiece 20 is rotated in timed relation to-the rotation .of wheel- 19 during forming of the teeth thereon. Wheel 19 .gener- .ates the gear from a;basic rack of the desired pitch which is .for-med on the peripheryof the wheelias a continuous helix. Thus the-opera i n is generallyxthat of .a gear hobber except that a grinding wheel has ;been substituted forthe conventional :hob. The work piecej20 is fed upward past the horizontal-center line of wheel 19 .as illustrated in Figure 4 todevelop the gear tooth form over the entire work face. 7 During the first phase work 20.:issimultaneously rolled back and forth across the full .width of wheel 19 to distribute .wheel wear.

The above description withreference to Figures l to 4 is of .pertinentdetailspf a known type gear grinding mach n gin whic t p e n igv nt nzi' mnl yed. -F.ig-

ures 5 to illustrate in detail the unique parallel drive forming the present invention.

Driving plate 25 has an upwardly extending boss 50 concentric with center 22 to which is attached by a wedge block 52 and screw 54 one end of a leaf spring 60 which extends radially outward from boss 50 and along the upper surface of plate 25.

At its radially outer end spring 60 is clamped between the lower ends of angled bars 62 and 64 forming a yoke 65. The upper ends of bars 62 and 64 carry adjustable screws 67 and 63 which are clamped against the outer end of a dog 70 extending radially from and clamped by screw 71 to the lower end of arbor 24 adjacent the upper surface of plate 25. Through leaf spring 60 and yoke 65 a resilient or yielding drive connection is fixedly connected between driving plate 25 and the work supporting arbor 24.

Arms 80 and 81 pivotally supported on plate 25 through pins 84 and $5 at each side of center 22 respectively provide clamping jaws 87 and 88 carrying screws 89 and '94) for gripping engagement with the lower ends of bars 62 and 64 connected to dog 70.

The opposite ends of arms 80 and 81 respectively pro vide follower surfaces 94 and '95 drawn into engagement with the surface of plate cam 97 by spring 98 connected through pins 99 and 109 to the arms. Cam 97 is pivoted on plate 25 by pin 101. As shown in Figure 6 cam 97 is positioned by stop pin 102 and separates follower surfaces 94 and 95 to firmly grip jaws 87 and 88 against yoke 65. This relationship is also shown in Figures 8 and 10. With cam 97 so positioned yoke 65 and dog 70 are positively connected to driving plate 25 throught a releasable drive parallel to that provided by leaf spring 60.

Cam 97 has an actuator 104 extending up above cover 105. manually prior to operation of the grinding machine to positively couple work piece to the intertiming drive which also drives grinding wheel 19. Provision is made for re-positioning cam 97 during operation to release the positive drive and render the resilient drive of spring 60 effective.

In the illustrated apparatus this operating structure is provided by a pin 107 slidable in a housing 108 carried by workhead 11 and urged by spring 110 to an outwardly retracted position. During operation, as driving plate rotates clockwise as in Figure 6, knob 112 is pushed manually inward to place the inner end of pin 107 in the path of actuator 104. This trips cam 97 counterclockwise as seen in this figure and followers 94 and 95 of arms 80 and 81 move toward one another to retract jaws 87 and 88 from yoke 65, thus releasing the positive driving connection.

In operation cam 97 is positioned to rock arms 80 and 81 in first directions and lock jaws 87 and 88 against yoke 65 and dog 70 to positively couple dog 70 to driving plate 25. After a first positive grinding phase has been completed and the basic work form completed knob 112 is positioned inward by the operator, moving pin 107 into path of cam actuator 104 to trip the cam and allow arms 80 and 81 to move in the reverse directions, releasing yoke 65 and dog 70 from the positive drive. The parallel resilient drive of leaf spring 60 is rendered efiective. Thus through this arrangement a second grinding phase is provided wherein control of workpiece 20 onarbor 24 is maintained through leaf spring 60 and the interdrive to wheel 19.

In this second phase drive the resilience of spring 60 dampens and isolates any vibration or oscillation disturbances from work piece 26 while maintaining driving control thereof. This makes possible improvement both in surface finish and in accuracy of the work during the second phase. During the resilient drive phase when wheel 14 is utilized to retract wheel head 12.frorn work piece 20, work gear 20 does not lag against the wheel surfaces but is driven in timed relation hip ther w Cam 97 is placed in the position of Figure 6 through leaf spring 60 and leave-01f marks or thinning is avoided irrespective of the speed of retraction of Wheel head 12.

Thus an improved drive for utilization in machines for grinding toothed work pieces has been provided which makes possible both accurate and properly finished work pieces without the deficiencies or difliculties of prior approaches. Through the parallel drives of the present invention work piece control is always maintained while selective positive and resilient drive phases are made possible.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. Apparatus for grinding toothed members such as gears and the like by means of a helically ribbed grinding wheel in a generating hob-type operation, comprising a base, a work support rotatably carried on said base, a helically ribbed grinding wheel, a spindle rotatable on said base carrying said grinding wheel, power means, first drive means operated by said power means between said support and said spindle including a positive driving interconnection, second drive means operated by said power means between said support and said spindle including a resilient driving interconnection for yieldingly transmitting power, and control means operatively associated with said first drive means for disabling said positive driving interconnection during a grinding operation to thereupon render said resilient drive interconnection effective.

2. Apparatus for grinding toothed members such as gears and the like by means of a helically ribbed grinding wheel in a generating hob-type operation, comprsing a base, a work support rotatably carried on said base, a helically ribbed grinding wheel, a wheel support rotatable on said base carrying said grinding wheel, drive means on said base including a timing interconnection, driving connections from said drive means to both said supports for rotation thereof in a predetermined timed relationship, the drive connection to one of said supports including first and second parallel drive means, the first of said drive means including a releasable positive drive connection, the second of said drive means including a yieldable drive connection fixedly included in the drive interconnection for yieldingly transmitting power, and control means operatively associated with said first drive means for releasing said positive drive connection to thereupon render said yielding drive connection effective.

3. Apparatus for grinding toothed members such as gears and the like by means of a helically ribbed grinding wheel in a generating hob-type operation, comprising a base, a work supporting arbor, a helically ribbed grinding wheel, a spindle rotatably carrying said wheel on said base, an arbor support rotatable on said base, power means connected to drive said spindle and said arbor support in timed relation, a driving dog connected to said arbor, first drive means between said support and said dog including releasable contact means for positive coupling therebetween, second drive means between said support and said dog including yieldable spring means fixedly connected therebetween, and control means operatively asso ciated with said first drive means for releasing said contact means during a grinding operation to thereby render said spring means drivingly effective for yieldingly transmitting power.

4. Apparatus for grinding toothed members such as gears and the like by means of a helically ribbed grinding wheel in a generating hob-type operation, comprising a base, a work supporting arbor, a helically ribbed grinding wheel, a wheel supporting spindle rotatable on said base, arbor support means rotatable on said base including a plate providing a live center supporting one arbor end.

a drive motor, driving interconnections between said motor and both said spindle and said plate, a driving dog connected to said arbor adjacent said plate, a leaf spring, means connecting one end of said spring to said plate, means clamping the other end of said leaf spring to said dog, a pair of arms symmetrically supported on said plate at each side of said center for pivoting movement about axes parallel to the center of rotation thereof, gripping jaws at corresponding ends of said arms for releasable engagement with opposite sides of said clamping means, adjustable cam means on said plate between the opposite ends of said arms for pivoting thereof in first directions to lock said jaws against said clamping means for positive driving interconnection between said plate and said arbor, and control means for actuating said cam means during grinding to pivot said arms in the reverse directions to retract said jaws and disable the positive drive connection, whereby said leaf spring is rendered etfective for yieldingly transmitting power and driving said arbor.

5. Apparatus for grinding toothed members such as gears and the like by means of a helically ribbed grinding wheel in a generating hob-type operation, comprising a base, a work support rotatab-ly carried on said base, a helically ribbed grinding wheel, a spindle rotatable on said base carrying said grinding wheel, power means, first drive means operated by said power means between said support and said spindle including a positive driving interconnection, second drive means operated by said power means between said support and said spindle including a radially extending yieldable spring blade yieldingly interconnecting said power means and said spindle for the yielding transmission of power therebetween, and control means operatively associated with said first drive means for disabling said positive driving interconnection during a grinding operation to thereupon render said spring blade effective for yielding transmission of power.

References Cited in the file of this patent UNITED STATES PATENTS Rickenmann Sept. 25, 1945 2,729,033 Prucknicki et al. Jan. 3, 1956 

